My ladies are now 7 and 9 weeks old. They've been living in my coop for a few weeks now but I kept a heat lamp in there as it gets chlly at night. How long should I keep the lamp in with them? Is it safe to stop now? I am on the coast, and we generally average highs in the high 60's to 70's and lows in the mid-50's. The RIR's have a lot of their feathers, the ameraucana still has a little ways to go.